Today I had an issue with a t-stat cover, that I thought was cracked or a water pump issue. Neither was the case, however I did get the
t-stat housing/cover and o-ring from Napa for 4.74 cents.. it was local, and didn't run me a arm or leg.
Handi Light and wienie whistle

Now the trick is, using a UV light. Yep, I had bought one to use on a/c systems looking for leaks as that dye fluoresces. But guess what?
So does good old fashioned Prestone anti-freeze.

A few months back I had a coolant leak that I couldn't find it was a itty-bitty one, never saw it, but I had to top my jug up. One day I got out my UV light and started going over every hose... and I found bright yellow crap on the block above that plastic water outlet flang, and there it was a tiny little crack, that showed up under uv.
Step forward to today, I took that lamp and checked over the hose clamp, and waterpump, and only saw yellow on the t-stat cover.
I remove the bolts and there it was a bright yellow spotted bolt hole....t-stat cover failure.. plain as the nose on your face.
I was removing the bolts and it was obvious to me that I didn't tighten it down as well as I should of and it was probably o-ring failure....
But what the hell 5bucks replace it.. no worries...... Just another dumbass me moment.... too tight and they crack, too loose and they leak.
Key here is the creative use of UV to find leaks..........